Factors Determining the Functional and Radiological Outcome after Secondary Nailing in Open Fractures of Lower Extremity- A Prospective Cohort Study

Introduction: Open long bone fractures of lower limb are cumbersome to treat. Because of the increased chances of infection, wound debridement and external fixation is the primary procedure followed by a secondary intramedullary nailing when the wound improves. Pin tract infection, loss of fixation, non union is the most frequently encountered complications of external fixation. These complications have discouraged surgeons all over the world in accepting external fixation as a definitive method of fracture treatment. Secondary intramedullary interlocking nailing provides intramedullary input of cancellous tissue at the fracture site due to reaming and nailing.

Aim: To evaluate the factors determining the outcome after secondary nailing in open fractures of lower extremity.

Materials and Methods: The prospective cohort study was conducted from October 2017 to April 2020 at Pondicherry Institute of Medical Sciences, Puducherry, India, with 33 patients who had open long bone fractures of lower limb and underwent secondary nailing following external fixation, were evaluated. The patients were followed-up for a period of six months. Factors such as age, bone involved, grade of injury, timing of debridement, time interval between external fixation and secondary nailing were analysed to see whether they affect the outcome of secondary nailing of open fractures of long bones. All patients underwent an initial thorough wound debridement and external fixation application. A secondary nailing was done once wound had settled down. Age, gender, bone involved, grade of injury, timing of debridement and timing of secondary nailing were noted for all the patients and patients were followed-up at six weeks, three months and six months. Final functional outcome (end of six months) was calculated using Lower Extremity Functional Scale (LEFS) and radiological union (end of six months) was calculated using Radiological Union Scale in Tibial fractures score (RUST).

Results: There were no statistically significant differences in RUST/LEFS score at the end of six months, with respect to age (p-value=0.825/0.847), gender (p-value=0.235/0.348), bone involvement (p-value=0.726/0.757), grade of injury (p-value=0.107/0.546) and timing of debridement (p-value=0.117/0.374). The mean RUST scores at six weeks, three months and six months were 4.39, 6.57 and 9.28, respectively. The mean LEFS scores at six weeks, three months and six months were 20.96, 34.92, 49.5, respectively. The radiological union rate in this study was 60.61% at the final follow-up. But patients who underwent secondary nailing with 10 days of primary debridement and external fixation had a statistically significant (p-value) better outcome in terms of RUST (p-value at 3 months=0.045)/LEFS (p-value at 6 months=0.030).

Conclusion: The interval between external fixation and secondary nailing was found to be a significant determinant of radiological outcome at three months (p-value at 3 months=0.045) and better functional outcome at six months (p-value at 6 months=0.030) with patients undergoing secondary nailing within 10 days of external fixation having a good final outcome. However, the radiological outcome between the two groups was comparable at six months follow-up